Exposures to phthalates and bisphenols in pregnancy and postpartum weight gain in a population-based longitudinal birth cohort

Maternal pre-pregnancy BMI influences the associations between bisphenol and phthalate exposures and maternal weight changes and fat accumulation

BACKGROUND

Bisphenols and phthalates are two classes of endocrine-disrupting chemicals (EDCs) thought to influence weight and adiposity. Limited research has investigated their influence on maternal weight changes, and no prior work has examined maternal fat mass. We examined the associations between exposure to these chemicals during pregnancy and multiple maternal weight and fat mass outcomes.

METHODS

This study included a sample of 318 women enrolled in a Canadian prospective pregnancy cohort. Second trimester urinary concentrations of 2 bisphenols and 12 phthalate metabolites were quantified. Self-reported and measured maternal weights and measured skinfold thicknesses were used to calculate gestational weight gain, 3-months and 3- to 5-years postpartum weight retention, late pregnancy fat mass gain, total postpartum fat mass loss, and late postpartum fat mass retention. Adjusted robust regressions examined associations between chemicals and outcomes in the entire study population and sub-groups stratified by pre-pregnancy body mass index (BMI). Bayesian kernel machine regression examined chemical mixture effects.

RESULTS

Among women with underweight or normal pre-pregnancy BMIs, MBzP was negatively associated with weight retention at 3- to 5-years postpartum (B = -0.04, 95%CI: -0.07, -0.01). Among women with overweight or obese pre-pregnancy BMIs, MEHP and MMP were positively associated with weight retention at 3-months and 3- to 5-years postpartum, respectively (B's = 0.12 to 0.63, 95%CIs: 0.02, 1.07). DEHP metabolites and MCNP were positively associated with late pregnancy fat mass gain and late postpartum fat mass retention (B's = 0.04 to 0.18, 95%CIs: 0.001, 0.32). Further, the mixture of EDCs was positively associated with late pregnancy fat mass gain.

CONCLUSION

In this cohort, pre-pregnancy BMI was a key determinant of the associations between second trimester exposure to bisphenols and phthalates and maternal weight changes and fat accumulation. Investigations of underlying physiological mechanisms, windows of susceptibility, and impacts on maternal and infant health are needed.

The effect of bisphenols on sex and thyroid hormone concentrations in cord blood among newborns

This study aims to investigate the associations of bisphenols with sex and thyroid hormones in cord blood among newborns. Four bisphenols, three hormones related to gonadal function, and four parameters related to thyroid function were measured in umbilical cord blood in 378 mother-newborn pairs. Multivariable linear regression, quantile-based g-computation (QGC), and Bayesian kernel machine regression were used. In the multivariable linear regression, bisphenol A (BPA) was associated with increased testosterone (TT) (regression coefficient, β = 0.049, 95% confidence interval, CI: 0.013,0.085; p = 0.007) and free tri-iodothyronine (FT3) levels (β = 0.019, 95% CI: 0.003, 0.035; p = 0.023), and decreased thyroid peroxidase antibody (TPOAb) (β = -0.053, 95% CI: 0.098, -0.008; p = 0.021). Consistently associations were observed in males, except TT, which was observed in females, and bisphenol AF (BPAF) was associated with decreased follicle-stimulating hormone (FSH) in females. These associations were also observed in a mixture of bisphenols. Moreover, we observed maternal prepregnancy body mass index (BMI) and delivery mode disparity in the relationship between bisphenols and sex and thyroid hormones. This study suggests that bisphenols may exert effects on sex and thyroid hormones in newborns, the effect may vary with sex differences, maternal prepregnancy BMI, and delivery mode.

An Evaluation of Food and Nutrient Intake among Pregnant Women in The Netherlands: A Systematic Review

Nutritional deficiencies during pregnancy can have serious consequences for the health of the (unborn) child. This systematic review provides an updated overview of the available food and nutrient intake data for pregnant women in The Netherlands and an evaluation based on the current recommendations. Embase, MEDLINE, and national institute databases were used. Articles were selected if they had been published since 2008 and contained data on food consumption, nutrient intake, or the status of healthy pregnant women. A qualitative comparison was made with the 2021 Dutch Health Council recommendations and reference values. A total of 218 reports were included, representing 54 individual studies. Dietary assessments were primarily performed via food frequency questionnaires. Protein, vitamin A, thiamin, riboflavin, vitamin B₆, folate, vitamin B₁₂, vitamin C, iron, calcium, and magnesium intakes seemed to be adequate. For folate and vitamin D, supplements were needed to reach the recommended intake. The reasons for concern are the low intakes of fruits, vegetables, and (fatty) fish, and the intakes of alcohol, sugary drinks, and salt. For several foods and nutrients, no or limited intake data were found. High-quality, representative, and recent data are needed to evaluate the nutrient intake of pregnant women in order to make accurate assessments and evaluations, supporting scientific-based advice and national nutritional policies.

Maternal exposure to phthalates and total gestational weight gain in the LIFECODES birth cohort

Excessive gestational weight gain contributes to adverse maternal and neonatal outcomes. Environmental exposures such as phthalates may lead to metabolic dysregulation, and studies suggest possible associations between maternal phthalate exposure and altered gestational weight gain. We assessed the association between nine maternal phthalate metabolites and measures of total gestational weight gain (pre-pregnancy to median 35.1 weeks of gestation) in a case-control study nested within LIFECODES (N = 379), a prospective birth cohort from Boston, Massachusetts (2006-2008). Our primary outcome was total gestational weight gain z score, a measure independent of gestational age that can provide a less biased estimate of this association. Our secondary outcomes were total gestational weight gain, rate of gestational weight gain, and adequacy ratio. The results were stratified by pre-pregnancy body mass index category. We found that concentrations of mono-(3-carboxypropyl) phthalate (MCPP) and mono-n-butyl phthalate (MBP) were positively associated with total gestational weight gain z scores among participants with obesity: adjusted mean difference (95% Confidence Interval [CI]) = 0.242 (0.030 - 0.455) and 0.105 (-0.002 - 0.212) corresponding to an excess weight gain of 1.81 kg and 0.77 kg at 35 weeks of gestation per interquartile range-increase in MCPP and MBP, respectively. Also, among participants with obesity, MBP demonstrated a potential non-linear relationship with gestational weight gain in cubic spline models. These findings suggest that phthalates may be related to higher gestational weight gain, specifically, among individuals with pre-pregnancy obesity. Future research should investigate whether pregnant people with obesity represent a subpopulation with sensitivity to phthalate exposures.

Inherited Epigenetic Hallmarks of Childhood Obesity Derived from Prenatal Exposure to Obesogens

Childhood obesity has reached epidemic levels in developed countries and is becoming a major cause for concern in the developing world. The causes of childhood obesity are complex and multifactorial, involving the interaction between individual genetics and environmental and developmental factors. Among the environmental factors, there is a growing interest in understanding the possible relationship between the so-called environmental obesogens and the development of obesity in children. Exposure to these obesogens such as phthalates, bisphenol A, or parabens, has been identified as a promoter of obesity through different mechanisms such as the alteration of adipocyte development from mesenchymal progenitors, the interference with hormone receptors, and induced inflammation. However, less attention has been paid to the inheritance of epigenetic modifications due to maternal exposure to these compounds during pregnancy. Thus, the aim of this review is to summarize the current knowledge of epigenetic modifications due to maternal exposure to those obesogens during pregnancy as well as their potential implication on long-term obesity development in the offspring and transgenerational inheritance of epiphenotypes.

The effects of phthalate exposure on metabolic parameters in polycystic ovary syndrome

BACKGROUND-AIM

Phthalates are known as endocrine disrupting chemicals which are present in wide-range of products. The objective of the study was to investigate whether phthalate exposure may attribute to the metabolic syndrome development in women with polycystic ovary syndrome (PCOS).

METHOD

The cross-sectional study involved 60 women in reproductive age with confirmed PCOS. Anthropometric and biochemical measurements were examined together with detected levels of ten phthalate metabolites measured by GC-MS in morning urine samples.

RESULTS

In this study at least one phthalate metabolite was detected in 51.7% of samples. Total phthalate metabolites urine concentrations were positively associated with BMI, waist circumference, waist-to-height-ratio (WtHR), leptin serum levels as well as lipid accumulation product (LAP) and visceral adiposity index (VAI). Mono-methyl-phthalate (MMP) levels was significantly correlated with WtHR, LAP and VAI. Additionally, total phthalate metabolites levels were significantly linked with fasting plasma glucose and HOMA index, whereas MMP concentrations were associated with fasting plasma glucose and insulin levels. Total cholesterol (TC) level was statistically significantly higher among PCOS women with detected phthalate metabolites compared to those without phthalates. The sum of all phthalates was correlated with LDL and triglyceride levels as well as TC/HDL. MMP concentrations were linked positively with TC, LDL and triglyceride levels as well as with TC/HDL. It is noteworthy that MMP concentrations were positively associated with testosterone serum levels while the total phthalate metabolites concentrations were also linked but with moderate significance.

CONCLUSIONS

The increased phthalate metabolites concentrations may interfere with obesity, glucose and lipid impairment in PCOS women. Additionally, testosterone serum levels can be disrupted by MMP.

Phthalate exposure is associated with more rapid body fat gain in midlife women: The Study of Women's Health Across the Nation (SWAN) Multi-Pollutant Study

Obesity is a major threat to health, but the etiology of obesity is incompletely understood. Phthalates, synthetic chemicals ubiquitous in the environment, are suspected to have obesogenic effects, but the relationship of phthalates and obesity in humans remains uncertain. We examined whether phthalate exposure was associated with body fat gain in midlife women. We analyzed data from 1369 women in the Study of Women's Health Across the Nation Multi-Pollutant Study. Eleven phthalate metabolites measured in spot urine samples at baseline (1999/2000) were standardized with covariate-adjusted creatinine. Body weight (BW), fat mass (FM) from dual-energy X-ray absorptiometry (DXA), and body fat percentage (BF%) from DXA were measured near-annually until 2016/2017. For each metabolite, linear mixed effects models with time and log2(metabolite) interactions were examined, adjusting for demographic, lifestyle, and menopause-related factors. Analyses were conducted overall and stratified by baseline obesity status. As sensitivity analyses, all analyses were repeated using a second set of metabolites measured in 2002/2003. Higher levels of all metabolites except mono-carboxy-isononyl phthalate were associated with faster increases in BF%. Per doubling of metabolite concentrations, differences in five-year BF% change ranged from 0.03 percentage point (ppt) (95% confidence interval (CI): -0.03, 0.09) for mono-isobutyl phthalate to 0.09 ppt (95% CI: 0.02, 0.16) for mono(3-carboxypropyl) phthalate. Results were similar for FM change, but associations with BW change were mostly null. In stratified analyses by baseline obesity status, positive associations were strongest in women who were normal/underweight at baseline. When metabolites from 2002/2003 were used as exposures, most associations were attenuated and not statistically significant, but they remained positive for normal/underweight women. In conclusion, phthalate metabolites were associated with more rapid body fat gain in midlife women, but our results need confirmation given attenuation of estimates in the sensitivity analyses.

Prenatal phthalates, gestational weight gain, and long-term weight changes among Mexican women

BACKGROUND

Phthalates are endocrine disrupting chemicals that may influence weight status; however, few studies have considered weight gain during pregnancy and subsequent long-term weight changes in women.

OBJECTIVE

To determine associations of prenatal phthalate exposure with maternal weight during pregnancy and through up to seven years post-delivery.

METHODS

We analyzed 15 urinary phthalate biomarker concentrations during the 2nd and 3rd trimesters among 874 pregnant women enrolled in the Programming Research in Obesity, Growth Environment and Social Stress Study in Mexico City. We examined three time-specific maternal weight outcomes: gestational weight gain (between 2nd and 3rd trimesters), short-term weight (between 3rd trimester and 12 months post-delivery), and long-term weight (between 18 months and 6-7 years post-delivery). We used Bayesian Kernel Machine Regression (BKMR) to estimate associations for the total phthalate mixture, as well as multivariable linear mixed models for individual phthalate biomarkers.

RESULTS

As a mixture, 2nd trimester urinary phthalate biomarker concentrations were associated with somewhat lower gestational weight gain between the 2nd and 3rd trimesters (interquartile range, IQR, difference: -0.07 standard deviations, SD; 95% credible interval, CrI: -0.20, 0.06); multivariable regression and BKMR models indicated that this inverse association was primarily driven by mono-2-ethyl-5-carboxypentyl terephthalate (MECPTP). Prenatal (2nd and 3rd trimesters) urinary phthalate mixture concentrations were positively associated with maternal weight change through 12 months postpartum (IQR difference: 0.11 SD; 95% CrI: 0.00, 0.23); these associations persisted from 18 months to 6-7 years follow-up (IQR difference: 0.07 SD; 95% CrI: 0.04, 0.10). Postpartum weight changes were associated with mono-3-carboxypropyl phthalate (MCPP) and MECPTP.

CONCLUSIONS

Prenatal phthalate exposure was inversely associated with gestational weight gain and positively associated with long-term changes in maternal weight. Further investigation is required to understand how phthalates may influence body composition and whether they contribute to the development of obesity and other cardiometabolic diseases in women.

REPRODUCTIVE TOXICOLOGY: Pregnancy exposure to endocrine disrupting chemicals: implications for women's health

Women are ubiquitously exposed to non-persistent endocrine disrupting chemicals (EDCs) from food contact materials and personal care products. Understanding the impacts of exposure to these chemicals on pregnancy and long-term health outcomes in women is a critical area of research that has been largely overlooked. This brief review focuses on the epidemiologic literature exploring associations of non-persistent EDCs - including phthalates, parabens, bisphenols, and triclosan - with maternal pregnancy outcomes and long-term health outcomes in women. We focus on the challenges of this research, particularly assessing non-persistent EDC exposures, aspects of study design, and statistical approaches. We conclude by reviewing the best practices for non-persistent EDC research with regards to pregnancy and women's health. Though limited, we found some evidence indicating that exposure to non-persistent EDCs is associated with pregnancy health. However, findings from these studies have been inconsistent and require corroboration. Recent studies have also proposed that non-persistent EDC exposures in pregnancy may adversely affect postnatal maternal health. To date, only a few studies have been conducted and have only focused on postpartum weight. More research is needed in this area to inform efforts to promote optimal health across the lifespan of women.

The associations of phthalate biomarkers during pregnancy with later glycemia and lipid profiles

BACKGROUND

Pregnancy induces numerous cardiovascular and metabolic changes. Alterations in these sensitive processes may precipitate long-term post-delivery health consequences. Studies have reported associations between phthalates and metabolic complications of pregnancy, but no study has investigated metabolic outcomes beyond pregnancy.

OBJECTIVES

To examine associations of exposure to phthalates during pregnancy with post-delivery metabolic health.

DESIGN

We quantified 15 urinary phthalate biomarker concentrations during the second and third trimesters among 618 pregnant women from Mexico City. Maternal metabolic health biomarkers included fasting blood measures of glycemia [glucose, insulin, Homeostatic Model Assessment of Insulin Resistance [HOMA-IR], % hemoglobin A1c (HbA1c%)] and lipids (total, high-density lipoprotein (HDL), low-density lipoprotein (LDL) cholesterol, triglycerides), at 4-5 and 6-8 years post-delivery. To estimate the influence of the phthalates mixture, we used Bayesian weighted quantile sum regression and Bayesian kernel machine regression; for individual biomarkers, we used linear mixed models.

RESULTS

As a mixture, higher urinary phthalate biomarker concentrations during pregnancy were associated with post-delivery concentrations of plasma glucose (interquartile range [IQR] difference: 0.13 SD, 95%CrI: 0.05, 0.20), plasma insulin (IQR difference: 0.06 SD, 95%CrI: -0.02, 0.14), HOMA-IR (IQR difference: 0.08 SD, 95% CrI: 0.01, 0.16), and HbA1c% (IQR difference: 0.15 SD, 95%CrI: 0.05, 0.24). Associations were primarily driven by mono-2-ethyl-5-carboxypentyl terephthalate (MECPTP) and the sum of dibutyl phthalate biomarkers (∑DBP). The phthalates mixture was associated with lower HDL (IQR difference: -0.08 SD, 95%CrI: -0.16, -0.01), driven by ∑DBP and monoethyl phthalate (MEP), and higher triglyceride levels (IQR difference: 0.15 SD, 95%CrI: 0.08, 0.22), driven by MECPTP and MEP. The overall mixture was not associated with total cholesterol and LDL. However, ∑DBP and MEP were associated with lower and higher total cholesterol, respectively, and MECPTP and ∑DBP were associated with lower LDL.

CONCLUSIONS

Phthalate exposure during pregnancy is associated with adverse long-term changes in maternal metabolic health. A better understanding of timing of the exact biological changes and their implications on metabolic disease risk is needed.

Maternal phthalate urine concentrations, fetal growth and adverse birth outcomes. A population-based prospective cohort study

IMPORTANCE

Exposure to phthalates may affect fetal growth, but previous studies are inconsistent and have not explored the trimester-specific effects of phthalates on repeated measures of fetal growth.

OBJECTIVE

To assess the associations of maternal phthalate metabolites urine concentrations with fetal growth measures and birth outcomes and identify potential windows of vulnerability to exposure.

DESIGN

Population-based prospective cohort study, the Generation R Study (2002-2006). Data analysis was performed from November 2019 to June 2020.

SETTING

Rotterdam, the Netherlands.

PARTICIPANTS

1379 pregnant women.

EXPOSURES

Maternal phthalate metabolites urine concentrations in first, second and third trimester.

MAIN OUTCOMES AND MEASURES

Fetal head circumference, length and weight measured in the second and third trimester by ultrasound and at birth and preterm birth and small size for gestational age at birth.

RESULTS

Higher pregnancy-averaged phthalic acid, low molecular weight phthalate (LMWP), high molecular weight phthalate (HMWP) and di-2-ethylhexylphthalate (DEHP) concentrations tended to be associated with lower fetal weight SDS across gestation. The associations of phthalic acid and LMWP with fetal weight became stronger as pregnancy progressed (differences -0.08 (95% CI -0.14 to -0.02) SDS and -0.09 (95% CI -0.16 to -0.02) SDS at 40 weeks per interquartile range increase in phthalic acid and LMWP, respectively). Higher concentrations of specific LMWP, HMWP and DEHP metabolites were also associated with smaller head circumference and lower length SDS at birth and an increased risk of preterm birth and small size for gestational age at birth (p-values < 0.05). We observed differences by timing of exposure in these associations.

CONCLUSIONS AND RELEVANCE

Higher maternal phthalate metabolites urine concentrations seem to be related with fetal growth restriction and preterm birth. Phthalates may have trimester specific effects on fetal growth and birth outcomes. Further studies are needed to explore the underlying mechanisms and long-term consequences.